It's a bit weird to present it as an alternative to S3 when it looks like a persistent cache or k/v store. A benchmark against Redis would have been nice for example. The benchmark for rocks DB is also questionable as the performance depends a lot on how you configure it, and the article's claim that it doesn't support range read doesn't give me confidence in the results.

Also for the descried issue of small images for a frontend, nobody would serve directly from S3 without a caching layer on top.

It's a interesting read for fun, but I am not sure what it solves in the end.